KR20230073768A - Can for secondary batteries having vent structure, and manufacturing mathod of the can - Google Patents

Abstract

The present invention relates to a can for a secondary battery having an integral vent capable of simplifying the manufacturing process and stabilizing quality by integrally molding vents that do not protrude to the outside together in the manufacturing process of the can, and is bent so that the upper and lower sides and A metal plate having a side surface and a rear surface; and a vent portion formed in an area of an upper surface of the metal plate member. Including, the bent part is integrally formed by a press process for the metal plate, the vent part has a thinner thickness than the metal plate, does not protrude on the horizontal surface of the metal plate, and has a vertical cross section in a 'W' shape. characterized by the formation of

Description

Secondary battery can and can manufacturing method having integrated vent

The present invention relates to a can for a secondary battery having an integral vent and a method for manufacturing the can, and more particularly, to integrally mold a vent that does not protrude to the outside together in a can manufacturing process to simplify the manufacturing process and to stabilize quality It relates to a secondary battery can having an integrated vent and a method for manufacturing the can.

In general, a lithium ion secondary battery includes an electrode plate assembly wound or stacked in a jelly roll form, a substantially hexahedron-shaped can into which the electrode plate assembly is inserted and fixed, and lithium ions filled in the can to allow movement of lithium ions. It consists of an electrolyte solution to do so, and a cap plate that blocks the can on top of the electrode plate assembly and the electrolyte solution.

In such a lithium ion secondary battery, after stacking a positive electrode plate attached with a positive electrode active material, a negative electrode plate attached with a negative electrode active material, and a separator, they are wound or laminated in a jelly roll form, put back into a can, and sealed by welding a cap plate on the top. do. Thereafter, after injecting the electrolyte solution, charging and inspection are performed to complete a bare cell type lithium ion secondary battery. Of course, a normal battery pack is completed by assembling and inspecting after attaching various safety devices and protection circuit boards to the bare cell type lithium ion secondary battery.

Meanwhile, since such a lithium ion secondary battery uses a constant voltage/constant current charging method, there is no overcharging phenomenon when the charging voltage is accurately controlled by the charger. However, there are cases in which the charger is damaged or malfunctions, resulting in abnormal charging. In this case, the battery voltage continues to rise due to the characteristic of the positive electrode active material, for example, lithium baltate (LiCoO2), whose potential continuously rises, and also causes abnormal charging. fever occurs.

Safety measures against this phenomenon include the incorporation of a positive temperature coefficient thermistor, the adoption of a separator with a shutdown function, and a protective circuit board that controls the charging and discharging voltage. There is a safety vent operated by

Here, the vent portion usually refers to a thinner area formed on the cap plate, which ruptures or breaks when the internal pressure of the battery rises due to gas generation and releases gas inside the can to the outside, thereby causing extreme extremes such as explosion of the lithium ion secondary battery. It plays a role in preventing incidents.

The gas is generated as the electrolyte or active material is decomposed when the charging voltage of the lithium ion secondary battery rises above the reference voltage. This gas usually causes the can to swell by increasing the internal pressure of the battery, and the vent part ruptures, ruptures, or ruptures due to the increase in the internal pressure of the battery, thereby preventing extreme explosion or fire of the lithium ion secondary battery. .

As such, the vent unit is designed to operate automatically when the internal pressure of the battery exceeds a predetermined pressure. However, since the conventional vent portion is processed to make a predetermined area of the cap plate relatively thin, there is a problem in that the operating speed of each battery is slightly different.

A vent structure of a battery according to the prior art forms a hole in a cap plate for a vent function, and adopts a method of bonding components having a separately formed vent structure through welding (laser) or thermal fusion.

However, this method has a problem of increasing manufacturing cost due to an increase in the number of parts and manufacturing processes, and a problem in that material management and process time increase because secondary processes necessary for welding and thermal fusion must be performed.

In accordance with this problem, recently, patents for constructing a vent part in a coining method in which a vent having a thickness smaller than that of other parts around the cap plate are formed have been disclosed (see Korean Patent Publication No. 2007-0071232).

However, this prior art has a problem in that the compression rate of the cap plate material is excessive in order to form the vent structure. In the prior art, when the bent structure is integrally formed, the difference between the molding thickness of the bent structure and the thickness of the cap plate is large, resulting in buckling, concentration of stress, and wrinkles caused by rapid changes in the material of the cap plate around the bent structure. There is a problem in that a defect in the cap plate itself occurs due to the occurrence of the cap plate itself. Therefore, these conventional technologies are evaluated as impossible technologies to be applied in practice.

Meanwhile, FIGS. 1 and 2 are views for explaining a can manufacturing process according to the prior art.

First, FIG. 1 is a perspective view of a state in which a molded tube body is cut into unit tube bodies during a can production process applied to a secondary battery. A process for producing a can used in a secondary battery includes a process of forming a tubular body 1 and cutting the tubular body 1 into unit tubular bodies 2. The tubular body 1 may be formed by extruding or drawing.

Next, FIG. 2 shows a process of welding the bottom plate 3 to the unit pipe body 2 of FIG. 1 . As a result, the can 5 is produced with only one surface corresponding to the bottom plate 3 open, and a cap plate for sealing the inside of the can 5 is attached to the open surface.

However, in such an existing process, since the can 5 is manufactured based on the cylindrical unit tube body 2, it is a structure inevitably forming a welded portion between the bottom plate 3 and the unit tube body 2, The welding portion is formed as long as the outer circumference length forming the four sides of the bottom plate (3). Accordingly, the possibility of leakage of the electrolyte solution from the welding portion increases. In addition, such an existing process has problems in that various equipment and materials are used for the production and cutting of the tubular body, as well as the increase in the number of manufacturing processes, resulting in increased manufacturing cost, and the total length of the welded part is long and the process time is increased.

Furthermore, when the charging voltage of the lithium ion secondary battery rises above the reference voltage, the internal pressure of the battery rises due to the generation of gas inside the can. cause a decrease in stability.

The present invention has been made to solve the above problems, and its object is to integrally mold the vents that do not protrude to the outside together in the manufacturing process of the can to simplify the manufacturing process and stabilize the quality. It is to provide a battery can and a method for manufacturing the can.

According to the present invention, the metal sheet is bent and has upper and lower surfaces and front and rear surfaces; and a vent portion formed in an area of an upper surface of the metal plate member. Including, the bent part is integrally formed by a press process for the metal plate, the vent part has a thinner thickness than the metal plate, does not protrude on the horizontal surface of the metal plate, and has a vertical cross section in a 'W' shape. Provided is a can for a secondary battery, characterized in that formed.

Preferably, the vent portion includes first and second protrusions of two parts protruding toward the inside of the can, a first concave portion formed between the first and second protrusions, and the first and second protrusions. It is characterized in that second and third concave portions are respectively formed on the outside of the second protrusion and connected to the non-press-processed metal plate.

Preferably, the concave depth of the first concave portion has a depth corresponding to that of the second and third concave portions.

Preferably, a notch is formed at the center of the inner surface of the first concave portion.

Meanwhile, according to another aspect of the present invention, a method for manufacturing a can according to any one of the above features, comprising: (a) preparing a flat metal plate; (b) forming a bent portion by pressing an upper side surface area of the metal plate with an upper mold and a lower mold; (c) forming a lower surface to be welded by first bending both side portions of the metal plate member to come into contact with each other; (d) secondarily bending the metal sheet material so that the upper side has the same area as the lower side, thereby forming front and back sides together with the upper side; (e) pressing the front and rear surfaces by tertiary bending to form a hollow prismatic structure; And (f) performing a laser welding along the coupling side in a state in which both coupling sides of the metal sheet are in contact with each other to weld and combine; It is characterized in that it includes.

Preferably, the metal plate is characterized in that it is formed of aluminum, aluminum alloy or conductive metal.

Preferably, a bending jig is used for the secondary bending of step (d), and the bending jig includes: an upper body; a connecting body connected to one side of the lower part of the upper body; a lower body in which the connector is connected to one side of the upper body to form a docking slit in a space spaced apart from the upper body; and a discharge slide formed at a position opposite to the connecting body. It is characterized in that it includes.

According to the present invention, the vents that do not protrude to the outside are integrally molded together in the manufacturing process of the can, thereby simplifying the manufacturing process and stabilizing the quality.

In addition, by bending the metal plate at an angle to form a can, the number of manufacturing processes is reduced and the manufacturing cost is lowered compared to the existing pipe body cutting method, and furthermore, the product assembly quality is improved and the quality can be stabilized.

1 and 2 are views for explaining a manufacturing process of a secondary battery can according to the prior art.
3 is a view for explaining a manufacturing process of a secondary battery can according to the present invention.
4 is a view for explaining a process of bending a plate of a can for a secondary battery according to the present invention.
5 is a view for explaining a process of assembling a cap plate of a can for a secondary battery according to the present invention.
6 is a view for explaining the appearance of an integral vent part of a can for a secondary battery according to the present invention.
7 is a view for explaining a manufacturing process according to the first embodiment of the integrated vent unit according to the present invention.
8 is a view for explaining a manufacturing process according to a second embodiment of the integrated vent unit according to the present invention.

Since the present invention can make various changes and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. Like reference numerals have been used for like elements throughout the description of each figure.

Terms such as first, second, A, and B may be used to describe various components, but the components should not be limited by the terms. These terms are only used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention. The terms and/or include any combination of a plurality of related recited items or any of a plurality of related recited items.

It is understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, but other elements may exist in the middle. It should be. On the other hand, when an element is referred to as “directly connected” or “directly connected” to another element, it should be understood that no other element exists in the middle.

Terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, the terms "include" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in the present application, they should not be interpreted in an ideal or excessively formal meaning. don't

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a view for explaining a manufacturing process of a secondary battery can according to the present invention.

Referring to (a) of FIG. 3 , the secondary battery can according to the present invention is formed by processing a flat metal plate 10 . The metal plate 10, which is the material of the can, forms the overall appearance of the secondary battery, and may be formed of a conductive metal such as aluminum, aluminum alloy, or nickel-plated steel.

Then, as shown in (b) of FIG. 3 , the bent portion 142 is formed by pressing the metal plate 10 in the region of the upper surface U with an upper mold and a lower mold. The vent part 142 is a structurally weak part designed to automatically operate when the internal pressure of the battery exceeds a predetermined pressure. A specific molding method of the vent portion 142 will be described in more detail with reference to FIGS. 6 to 8 hereinafter.

After that, as shown in (c) of FIG. 3, both sides of the flat metal plate 10 are primarily bent to form a lower surface L to be welded by contacting each other.

And as shown in (d) of FIG. 3, the plate material 10 is secondarily bent so that the upper side surface U has the same area as the lower side surface L, and the front side surface together with the upper side surface U. (F) and the rear side (B) are also formed. By bending the flat metal plate 10 four times in the same direction to form the front and rear sides and the upper and lower sides, the left and right sides are opened to make a hollow rectangular structure.

A bending jig may be used for the secondary bending.

Referring to FIG. 4, the bending jig has an upper body 110, a connector 120 connected to one lower side of the upper body 110, and the connector 120 connected to one upper side. It may be configured to include a lower body 130 forming a docking slit 121 in a space spaced apart from the upper body 110, and a discharge slide 140 formed at a position opposite to the connecting body 120. there is.

The overall length of the upper body 110 is formed longer than the length of the left and right sides of the can, and in particular, except for the connecting portion 120 connected to the lower part of the upper body 110 and the discharge slide 140, It should be formed longer than the left and right length of the can. In addition, the upper surface 111 of the upper body 110 is a long plane having a width corresponding to the width of the upper surface U of the can. In addition, the side surface 112 of the upper body 110 is formed shorter than the upper and lower lengths of the can, so that the firstly bent sides of the can can enter the docking slit 121 during the second bending process.

The docking slit 121 functions as a position where both sides of the first bent lower surface L of the can meet in the second bending process, and the overall length is longer than the left and right lengths of the can.

The ejection slide 140 is arranged so that the secondly bent can can smoothly come out of the bending jig. It is formed thin enough to come out.

The secondary bending process of the can through such a bending jig is shown in FIG. 4 .

First, as shown in (a) of FIG. 4, a flat metal plate 10 in which both sides are primarily bent by primary bending is introduced, and the upper surface U of the metal plate 10 is It is disposed on the upper surface 111 of the upper body 110.

Thereafter, as shown in (b) of FIG. 4, the metal plate 10 is pressed by the pressing means provided on both sides, and the front side F and the rear side ( B) is formed. In this process, the lower surface L of the metal plate 10 enters the docking slit 121 .

And as shown in (c) and (d) of FIG. 4, both side portions of the primary bent lower surface (L) of the can in a spaced apart state without being completely coupled come out through the discharge slide 140 As a result, the secondary bending process is completed.

On the other hand, when the secondary bending is completed in this way, as shown in FIG. The coupling sides of both ends of ) meet on the lower side (coupling surface), and are welded together by welding along the coupling sides in a state in which both coupling sides are in contact.

It is preferable that laser welding is applied to the welding of the coupling side, which has a high energy density like an electron beam and has little thermal deformation of the welded material or deterioration of material properties because it is fused narrowly and deeply.

As shown in FIG. 5 , the secondary battery can manufactured as described above will be structured in a substantially hexahedral shape by attaching cap plates 20 to the open left and right sides, respectively, so that the inside is sealed. An electrode plate assembly wound or stacked in the form of a jelly roll and an electrolyte solution filling the inside to enable movement of lithium ions may be embedded in the secondary battery can.

Here, when the charging voltage of the lithium ion secondary battery rises above the reference voltage, the internal pressure of the battery rises due to the generation of gas inside the can, and the vent part 142 is ruptured or broken to provide a discharge path for internal gas. .

6 is a view for explaining the appearance of an integral vent part of a can for a secondary battery according to the present invention.

In the present invention, the vent portion 142 is formed integrally with the metal plate 10 through press working in which the metal plate 10 is interposed between the upper mold and the lower mold and a predetermined pressure is applied.

In the secondary battery can, the vent portion 142 is ruptured or broken when the internal pressure of the battery increases, thereby reducing the internal pressure of the battery and preventing the battery from exploding.

To this end, the vent part 142 in the present invention is a part to be physically ruptured or broken, so it is processed to a relatively thin thickness (compared to the metal plate 10), so the stress against internal pressure is greater than other parts. to lose This thin thickness has a property that is relatively close to brittle fracture compared to other parts, so that it is possible to have a vent structure that can be ruptured or broken more quickly and accurately.

In addition, the upper mold and the lower mold used during press processing of the metal plate 10 include molding parts capable of forming the bent part 142, so in the can of the present invention, the bent part 142 is integrally formed by the pressing process. to be molded into

As shown in FIG. When viewed from the top and bottom sides, since the convex and concave portions are formed to have a repeated concave-convex shape, they do not protrude from the horizontal surface of the metal plate 10 in shape, resulting in excellent product quality and compatibility with other products.

6(b) is a cross-sectional view of the vent part 142.

The cross section of the vent part 142 is formed in a 'W' shape as a whole.

Accordingly, two portions of first and second protrusions P1 and P2 protruding toward the lower side, that is, toward the inside of the can, are formed, and a concave second portion between the first and second protrusions P1 and P2 is formed. 1, a concave portion D1 is formed, and second and third concave portions D2 are respectively concave at a portion connected to the non-press-processed metal sheet 10 outside the first and second protrusions P1 and P2. , D3) is formed. Here, the concave depths of the first concave portion D1 and the second and third concave portions D2 and D3 are the same.

When the internal pressure of the battery rises inside the can, this pressure is concentrated in the vent portion 142 having a thinner thickness than the metal plate 10 . Furthermore, the ejection pressure will be concentrated in the first to third concave portions D1 , D2 , and D3 of the vent portion 142 .

At this time, in the present invention, the notch N is formed on the inside of the first concave portion D1, that is, on the surface facing the inside of the can, so that the ejection pressure is concentrated in the first concave portion D1. This notch N will be a more deeply concave portion in the first concave portion D1, and will be a more deeply concave portion than the other second and third concave portions D2 and D3.

Therefore, the notch N of the first concave portion D1 has the thinnest thickness in the vent portion 142 and is structurally weak, and furthermore, among the weak parts of the bent portion 142, the first concave portion D1 Since the notch (N) is the most deeply concave part, the internal pressure is most concentrated, and the possibility of breakage of the corresponding part can be dramatically increased.

Moreover, since the first and second protrusions P1 and P2 are disposed around the notch N of the first concave portion D1, the oblique peripheral portion is connected around the notch N. . This oblique peripheral area will make the broken area easily lifted when the notch N of the first concave portion D1 is broken, and will prevent the discharge path of the internal gas from being blocked after the breakage.

7 is a view for explaining a manufacturing process according to the first embodiment of the integrated vent unit according to the present invention.

First, as shown in (a) of FIG. 7, a protruding embossed portion 142a is formed on the upper surface of the bent portion 142 of the metal plate 10 using cutting equipment, and a concave intaglio is formed on the lower surface. Part 142b is molded.

Then, as shown in (b) of FIG. 7, the embossed portion 142a is removed by horizontal cutting using cutting equipment.

Then, as shown in (c) of FIG. 7 , pressing is performed with an upper mold and a lower mold to form a vent portion 142 having a 'W'-shaped cross section as a whole.

At this time, the vent part 142 is formed with first and second protrusions P1 and P2 of two parts protruding toward the lower side, that is, the inside of the can, and between the first and second protrusions P1 and P2. A first concave portion D1 is formed at one portion of the first and second concave portions D1, and second and second concave portions are connected to the non-press-processed metal plate 10 outside the first and second protrusions P1 and P2, respectively. Third concave portions D2 and D3 are formed. Here, the concave depths of the first concave portion D1 and the second and third concave portions D2 and D3 are the same.

Subsequently, as shown in (d) of FIG. 7 , a notch N is formed at the most deeply concave part inside the first concave portion D1 by using a notch device. This notch N will be a more deeply concave portion in the first concave portion D1, and will be a more deeply concave portion than the other second and third concave portions D2 and D3.

8 is a view for explaining a manufacturing process according to a second embodiment of the integrated vent unit according to the present invention.

First, as shown in (a) of FIG. 8, in the manufacturing process according to the second embodiment, the metal plate 10 is used as it is.

After that, as shown in (b) of FIG. 8, a concave concave portion 142b is formed on the lower surface of the bent portion 142 by using cutting equipment.

Then, as shown in (c) of FIG. 8, pressing is performed with an upper mold and a lower mold to form a vent portion 142 having a 'W'-shaped cross section as a whole.

At this time, the vent part 142 is formed with first and second protrusions P1 and P2 of two parts protruding toward the lower side, that is, the inside of the can, and between the first and second protrusions P1 and P2. A first concave portion D1 is formed at one portion of the first and second concave portions D1, and second and second concave portions are connected to the non-press-processed metal plate 10 outside the first and second protrusions P1 and P2, respectively. Third concave portions D2 and D3 are formed. Here, the concave depths of the first concave portion D1 and the second and third concave portions D2 and D3 are the same.

Subsequently, as shown in (d) of FIG. 8 , a notch N is formed at the most deeply concave part inside the first concave portion D1 by using a notch device. This notch N will be a more deeply concave portion in the first concave portion D1, and will be a more deeply concave portion than the other second and third concave portions D2 and D3.

As described above, the optimal embodiment has been disclosed in the drawings and specifications. Although specific terms have been used herein, they are only used for the purpose of describing the present invention and are not used to limit the scope of the present invention described in the claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

10: metal plate 142: bent part

Claims (7)

A metal plate material that is bent and has upper and lower surfaces and front and rear surfaces; and
a vent portion formed in an area of an upper side of the metal plate member; Including,
The vent part is integrally formed by a press process for a metal plate,
The can for a secondary battery, characterized in that the vent portion has a thickness smaller than that of the metal plate, does not protrude on a horizontal surface of the metal plate, and has a 'W'-shaped vertical cross section.
According to claim 1,
The vent part,
First and second protrusions of two parts protruding toward the inside of the can are formed,
A first concave portion is formed between the first and second protrusions,
A secondary battery can, characterized in that second and third concave portions, respectively, are formed at portions outside the first and second protrusions that are connected to the non-press-processed metal plate.
According to claim 2,
The secondary battery can, characterized in that the concave depth of the first concave portion has a depth corresponding to the concave depth of the second and third concave portions.
According to claim 3,
A secondary battery can, characterized in that a notch is formed at the center of the inner surface of the first concave portion.
A method for manufacturing the can according to any one of claims 1 to 4,
(a) preparing a flat metal plate;
(b) forming a bent portion by pressing an upper side surface area of the metal plate with an upper mold and a lower mold;
(c) forming a lower surface to be welded by first bending both side portions of the metal plate member to come into contact with each other;
(d) secondarily bending the metal sheet so that the upper side has the same area as the lower side, thereby forming front and back sides together with the upper side;
(e) pressing the front and rear surfaces by tertiary bending to form a hollow prismatic structure; and
(f) performing laser welding along the coupling sides in a state in which both coupling sides of the metal plate are brought into contact with each other to perform welding coupling; Method for manufacturing a can comprising a.
According to claim 5,
The method of manufacturing a can, characterized in that the metal plate is formed of aluminum, aluminum alloy or conductive metal.
According to claim 5,
A bending jig is used for the secondary bending in step (d),
The bending jig,
upper upper body;
a connecting body connected to one side of the lower part of the upper body;
a lower body in which the connector is connected to one side of the upper body to form a docking slit in a space spaced apart from the upper body; and
a discharge slide formed at a position opposite to the connecting body; Method for manufacturing a can comprising a.

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